Approximate computing is capable of exploiting the error resilience of various applications with the aim of improving their parameters such as performance, energy consumption and area on a chip.
Firstly, you should to make a systems analysis of your design task, that includes the elaboration of the conceptual mathematical model, it decomposition, elaboration of the mathematical models of each obtained subtask and to develop the solution tools (synthesis stage) of the original task. I am attaching a monographic work in which you can find a methodology that could help you to develop your research work.